A COMPARATIVE STUDY OF THE SAFETY AND EFFICACY OF DYSPROSIUM-165 HYDROXIDE MACRO-AGGREGATE AND YTTRIUM-90 SILICATE COLLOID IN RADIATION SYNOVECTOMY--A MULTICENTRE DOUBLE BLIND CLINICAL TRIAL

The aim of our study was to compare the safety and efficacyof a new preparation, Dysprosium-165 Hydroxide Macro-aggregate(¹⁶⁵Dy) with Yttrium-90 Silicate (⁹⁰Y) for radiation synovectomyof the knee in patients with RA and OA. A multicentre doubleblind clinical trial with subjects randomized to receive ¹⁶⁵Dyor ⁹⁰Y was undertaken in Sydney, Melbourne and Perth. Seventyknees of 59 patients were studied, using as clinical end pointmeasurements pain in the knee on walking, pain in the knee atrest and stiffness in the knee after rest. Cytogenetic damage,knee retention and extra-articular spread of the radionuclideto regional lymph nodes, liver, urine and blood were evaluated.There was no significant difference in clinical response inthe two treatment groups for either RA or OA. Chromosomal changesoccurred with equal frequency and the knee retention and extra-articularleakage of radiocolloids to regional lymph nodes and liver werecomparable in the two groups. For radiation synovectomy of theknee, ¹⁶⁵Dy is at least as safe and as effective as ⁹⁰Y andhas the advantage of a short half-life (2.334 h) and hence requiresa shorter period of post-injection immobilization and hospitalization. KEY WORDS: Radiation synovectomy, Dysprosium-165, Yttrium-90, Rheumatoid synovitis, Osteoarthritis